Interactions

Interactions with Drugs

In theory, the high iodine content of bladderwrack may interfere with the function of drugs that act on the thyroid such as levothyroxine (Synthroid®, Levoxyl®). Use of bladderwrack and amiodarone may alter thyroid function due to high iodine levels in both agents. Use of iodine-containing agents such as bladderwrack or kelp may alter thyroid function when used with lithium. Other endocrine hormones, estrogen levels, and progesterone levels may be affected and therefore bladderwrack may interacte with hormonal drugs.

Extracts of bladderwrack may cause lowered blood sugar. Caution is advised when using medications that may also lower blood sugar. Patients taking drugs for diabetes by mouth or insulin should be monitored closely by a qualified healthcare provider. Medication adjustments may be necessary.

Laxative properties have traditionally been attributed to chronic use of bladderwrack and other brown seaweeds and may be due to the component alginic acid, present in many laxative agents. Combination with laxatives may cause an additive effect. In theory, due to thyroid stimulant properties, bladderwrack may cause additive effects if taken with stimulants. The presence of heavy metal contaminants in bladderwrack preparations, including arsenic, cadmium, chromium, or lead, may increase the risk of kidney toxicity if taken with drugs that cause kidney damage. Bladderwrack may interact with diuretics.

Interactions with Herbs and Dietary Supplements

Extracts of bladderwrack may lower blood sugar levels. Caution is advised when using herbs or supplements that may also lower blood sugar. Blood glucose levels may require monitoring, and doses may need adjustment.

Bladderwrack may increase the risk of bleeding when taken with herbs and supplements that are believed to increase the risk of bleeding. Multiple cases of bleeding have been reported with the use of Ginkgo biloba, and fewer cases with garlic and saw palmetto. Numerous other agents may theoretically increase the risk of bleeding, although this has not been proven in most cases.

Laxative properties have traditionally been attributed to the chronic use of bladderwrack and other brown seaweeds, and may be due to the component alginic acid, present in many laxative agents. Combination with laxatives may cause an additive effect.

In theory, due to thyroid stimulant properties, bladderwrack may cause additive effects if taken with herbs or supplements with stimulant-type activity, such as caffeine, guarana, or ephedra (ma huang). The presence of heavy metal contaminants in bladderwrack preparations, including arsenic, cadmium, chromium, or lead, may increase the risk of kidney toxicity if taken with herbs or supplements that can cause kidney damage.

In theory, bladderwrack may decrease iron absorption, especially if ingested for a prolonged period of time. Bladderwrack preparations contain variable levels of calcium, magnesium, potassium, sodium, vitamins, and minerals and may therefore increase corresponding blood levels. Bladderwrack may interact with diuretics.